Engineering a High-Energy-Density and Long Lifespan Aqueous Zinc Battery via Ammonium Vanadium Bronze

Aqueous rechargeable zinc batteries (ARZBs) are desirable for energy storage devices owing to their low cost and abundance of the Zn anode, but their further development is limited by a dearth of ideal cathode materials that can simultaneously possess high capacity and stability. Herein, we employ a layered structure of ammonium vanadium bronze (NH₄)_0.5V₂O₅ as the cathode material for ARZBs. The large interlayer distance supported by the NH₄⁺ insertion not only facilitates the Zn²⁺-ion intercalation/deintercalation but also improves the electrochemical stability in ARZBs. As a result, the layered structural (NH₄)_0.5V₂O₅ cathode delivers a high capacity up to 418.4 mA h g^-1 at a current density of 0.1 A g^-1. A reversible capacity of 248.8 mA h g^-1 is still retained after 2000 cycles and a capacity retention of 91.4% was maintained at 5 A g^-1. Furthermore, in comparison with previously reported Zn-ion batteries, the Zn/(NH₄)_0.5V₂O₅ battery achieves a prominent high energy density of 418.4 W h kg^-1 while delivering a high power density of 100 W kg^-1. The results would enlighten and push the ammonium vanadium compounds to a brand new stage for the application of aqueous batteries.